Wills and Kate's emotional appeal for starving children

The Duke and Duchess of Cambridge today issued a worldwide appeal on behalf of 13million victims of the African famine - their first joint humanitarian mission.

The couple want to use their global fame to draw attention to the deepening crisis and they could visit the relief effort in the Horn of Africa next year.

The "first famine of the 21st century" has now spread from Somalia to Kenya, where William proposed to Kate a year ago, and more than 320,000 children are at risk of death after the worst drought in 60 years.

The royal couple will fly to Denmark next Wednesday to visit Unicef's emergency food distribution centre and will join the crown prince and crown princess of Denmark in publicising the relief effort. The trip has been arranged at short notice during a gap in William's helicopter search and rescue duties. Unicef's Supply Centre has a warehouse within it the size of three football pitches. It sources, packs and distributes essential supplies for children around the globe, including food, water, vaccines and emergency medical kits.

A St James's Palace spokesman said: "The Duke and Duchess have been deeply moved over the past few weeks by the desperate plight of hundreds of thousands of seriously ill children in East Africa, a part of the world they know well and which is dear to them.

"Going to Copenhagen to view the supplies heading out to the famine zones was their idea as they are very troubled by the situation. The British public have already been very generous, but the royal couple wish to do what they can to help to help maintain global attention on the worsening situation."

Britain is the third biggest donor to the crisis after giving £128million since July, with an emergency public appeal raising a further £72million. But there is concern that other wealthy nations such as France, Germany, Italy and some Arab nations have not been pulling their weight. British aid has fed 2.4million people and vaccinated millions against measles and polio. But problems are set to escalate with the arrival of rains spreading waterborne diseases.

International Development Secretary Andrew Mitchell said: "It is vital the international community steps up its commitments to help these desperate people."

Famine was declared three months ago in parts of Somalia when crops failed and livestock died after two years of no rain. Kenya, Djibouti and Ethiopia have also suffered dire food shortages and fleeing refugees. Problems have been made worse by the failure of governments to finance agriculture and irrigation schemes and parts of Somalia being under the control of Islamist militias linked to al Qaeda.

Elhadj As Sy, Unicef's regional chief of eastern and southern Africa, said: "As we speak, more than 320,000 children are in grave danger. We need every single person to help us continue our work, so please donate today at eastafricacrisis.org."